Measures to describe the severity of patient injuries are essential in adjusting for case mix differences between facilities to evaluate the association between the quality of EMS care and outcome. The most commonly used measure in trauma is Baker's ISS Injury Severity Scale which forms a basis for evaluation and resource allocation judgements in the EMS and automotive design research. Nevertheless, the ISS has not been well validated nor its reliability assessed except for preliminary and limited efforts of the present investigators. This project will, therefore examine various aspects of the reliability and validity of the ISS and its underlying AIS scoring mechanism in order to determine the appropriate data base and skill/training level for coders for reliable ISS usage to judge whether the AIS,ISS has acceptable levels of reliability and validity for both vehicular and non-vehicular injuries, to suggest revision for the AIS coding manual, and to organize a research conference to disseminate the results and provide an opportunity for open discussion about injury scaling in emergency medical care services research.